1. Technical Field
The present invention relates to a motion analysis method and a motion analysis device.
2. Related Art
For example, in golf, which is a specific example of sports, the concept of the swing plane is commonly known. The swing plane is equivalent to the trajectory of the golf club when swung. For example, according to JP-A-2009-20897 and JP-A-2008-23036, a golf swing made by a subject is shot with a camera from behind the subject and the swing plane is specified based on the shot image.
The technique for finding the swing plane according to JP-A-2009-20897 is to find at least two specific points in the swing from image data and analyze the swing plane based on the two points. In this technique, first, after the swing is finished, it is necessary to edit the image data and carry out work to find specific points. Therefore, there is a problem that a large discrepancy from the actual swing plane is generated and also a problem that it is time-consuming to display the swing plane. The technique of JP-A-2008-23036, too, requires some work to edit image data and therefore has similar problems to those of JP-A-2009-20897.
In golf swing coaching, indicators such as shaft plane and Hogan plane are known. The shaft plane is a plane formed by the direction of the longitudinal axis of the shaft of the golf club when the golfer is at address position (static state) and a target line (ball hitting direction). The Hogan plane is a plane formed by an imaginary line connecting the neck bottom (bottom of the neck) of the golfer and the ball when the golfer is at address position and a target line (ball hitting direction). An area between the shaft plane and the Hogan plane is called V-zone. The V-zone is defined when the golfer is at address position, and whether the ball hitting is good or not is evaluated, based on whether the golf club is in the V-zone at impact or not. If the shaft plane and the Hogan plane are shown as indicators on an image, the golfer can easily grasp points of improvement in the swing form. However, in the techniques of JP-A-2009-20897 and JP-A-2008-23036, in order to find the Hogan plane, it is necessary to shoot the form of the golfer from behind and manually draw lines with a ruler or the like, based on the shot image. Therefore, there are no previous measures to present the shaft plane and the Hogan plane easily and accurately to the golfer in golf swing analysis.